Liquid Molasses: A Potential Solution For Bridging The Energy Gap In Early Lactation
By: Sydney Moore, MSc. & Kaitlyn Dancy, MSc.
The negative energy balance dilemma
Following the onset of lactation, there is an increased demand of energy and nutrients needed from the cow to support milk synthesis. During the first few weeks of lactation, dairy cows often do not consume enough feed (or sufficient dry matter intake) to meet the nutrient requirements of supporting milk production. As a result, cows will experience a state of negative energy balance (NEB) where their body fat is mobilized as a source of energy. In severe cases of NEB, cows may develop subclinical ketosis (SCK), a metabolic disorder that can negatively impact milk production, reproductive success and increase the risk of a variety of other health disorders as well. Research has also shown that cows milked in automated milking systems (AMS) may be at an even higher risk for developing SCK, due to the increased energy demands of higher milking frequencies/milk yields possible in these herds. So what should we do? How do we support our cows and encourage them to remain at a high production level without inflicting negative consequences on the animal? The answer just may be sweeter than you think… Sugar supplementation has been shown to have many positive effects on cow metabolic health and production throughout their lactation!
Why is adding molasses to the diet the solution?
Sugar supplementation (particularly in the form of a molasses-based liquid feed), supports microbial growth, particularly for fiber-digesting bacteria. This allows for faster fiber degradation in the rumen and likely greater feed intake. In theory, supplementing molasses to fresh cows should encourage DMI and thus reduce the impact of negative energy balance seen postpartum. Sugar also is able to provide additional energy without increasing the risk of subacute ruminal acidosis, a common side effect of feeding excess starch in the diet.
Molasses in total mixed rations
Previous research has looked at the effects of feeding a molasses-based liquid feed within a lactating TMR. Researchers from the University of Guelph found that feeding mid-lactation cows a molasses-based liquid feed (~4% dietary DM) within a TMR has the ability to increase DMI, milk yield, and component yields of lactating cows. Similarly, researchers from the U.S. Dairy Forage Research center, found that increasing molasses in the diets of peak-mid lactation dairy cows correlated to an increase in daily dry matter intake. Additionally, researchers from the University of Alberta reported that replacing cracked corn with dietary sugar (~5%) for fresh cows, improved rumen health, DMI, milk production and improved energy balance parameters by reducing concentrations of plasma NEFA and BHB.
Molasses in automated milking systems
Recently, a study was conducted by the University of Guelph to investigate how molasses supplementation through AMS of 6 farms could influence fresh cow metabolic health. Cows enrolled in this study, were assigned to either a liquid feed group where they received their AMS pellet and an additional amount of a molasses-based liquid feed (~1kg/DM) each time they visited the robot to be milked, or to a control group, where cows only received the AMS pellet (and no molasses) at each milking event. Cows receiving molasses at the AMS had fewer repeat positive ketotic tests and lower blood BHB levels overall at approximately 15 DIM. Additionally, cows receiving the molasses in this study were able to maintain a more stable body condition score (i.e. lost less body condition) across the first 60 DIM compared to control cows.
Summary
Supplementing molasses to lactating dairy cows can result in benefits for cow milk production, rumen health and feed efficiency. Feeding of these sugars (specifically a molasses-based liquid feed) to fresh cows can help reduce the severity of negative energy balance experienced by the animal during such a vulnerable period of time. By feeding fresh cows a molasses-based liquid feed, daily feed intake (and or DMI) should increase, while decreasing energy balance parameters like BHB and NEFA. The sooner we are able to bridge this early lactation energy gap, the sooner we can see better production, health and welfare outcomes for our animals.
